Prove that all triangles obc are equal to oad
So oc = op, BC = AP
Because the angle COP = 90 degrees
So CP = radical 2po
So Pb-pa/po = Pb-PC/po = PC/po = root number 2.
2. Solution: Angle OAC = 90°, even ae, af, ef.
Prove that aof of triangle is equal to aoc.
So ce = of
So OE-of = OE-CE = OC = root number 2ao = 2 times root number 2.